Booklet binding apparatus and image forming system

ABSTRACT

A booklet binding apparatus including a clamp mechanism for clamping a sheet bundle, a coating member for applying adhesive to the spine surface of the sheet bundle clamped by the clamp mechanism, and an attaching and detaching mechanism for moving the coating member to and from the spine surface of the sheet bundle, wherein the attaching and detaching mechanism includes a separation mechanism which makes the coating member to be detached from the spine surface of the sheet bundle when an abnormal incident has occurred during application of the adhesive.

This application is based on Japanese Patent Application No. 2005-251003filed on Aug. 31, 2005 in Japanese Patent Office, the entire content ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to a booklet binding apparatus which producesbooklets by adhesion and to an image forming system equipped with thebooklet binding apparatus.

Because of the advantages of meeting the requirements for small lotproduction, shorter delivery time and reduced costs, an image formingapparatus based on color electrophotographic technology has come intouse in recent years to take the place of the conventional printingapparatus. The use of a booklet binding apparatus also has beenconsidered, wherein a predetermined number of the sheets with an imageformed thereon by an image forming apparatus are aligned to form abundle of sheets and a paste is applied to the spine surface of thebundle of sheets so that a cover sheet is bonded thereon for producing abooklet.

Among such kinds of booklet binding apparatuses, for the purpose of anenhancement of workability and quality, an apparatus which appliesadhesive to the spine surface of the sheet bundle and attaches a coversheet to the sheet bundle has been disclosed, wherein the edges of thecover sheet can be easily aligned to the edges of the sheet bundle onthe opposite side of the spine portion and firmly glued to the sheetbundle (Patent Document 1, for example).

However, if electric power to the book binding apparatus of PatentDocument 1 is shut off accidentally or involuntarily by the operatorwhile the adhesive application is in progress, the coating roller may bestuck to the spine surface of the sheet bundle with the adhesive and itmay take long time and much labor to separate the coating roller fromthe bundle of sheets when recovering the apparatus. Particularly, when ahot-melt adhesive is used to shorten bonding time and to obtain a strongbonding force, it may require more time and labor to melt the adhesiveand separate the coating roller from the sheet bundle.

[Patent Document 1] Unexamined Japanese Patent Application PublicationNo. 2004-209753

SUMMARY

The present invention includes the following structures:

(1) A booklet binding apparatus including: a clamp mechanism forclamping a bundle of sheets; a coating member for coating adhesive on anend surface of the bundle of sheets clamped by the clamp mechanism; anattaching and detaching mechanism for attaching the coating member tothe end surface of the bundle of sheets and for detaching the coatingmember from the end surface; and a separation mechanism for detachingthe coating member from the end surface of the bundle of sheets, when anabnormal incident occurs during coating of adhesive on the end surfaceof the bundle of sheets by the coating member.

(2) An image forming system including: an image forming apparatus havingan image forming section for forming an image on a sheet; a bookletbinding apparatus for producing a booklet by receiving a plurality ofsheets from the image forming apparatus, the booklet binding apparatushaving; a clamp mechanism for clamping a bundle of sheets; a coatingmember for coating adhesive on an end surface of the bundle of sheetsclamped by the clamp mechanism; an attaching and detaching mechanism forattaching the coating member to the end surface of the bundle of sheetsand for detaching the coating member from the end surface; and aseparation mechanism for detaching the coating member from the endsurface of the bundle of sheets, when an abnormal incident occurs duringcoating of adhesive on the end surface of the bundle of sheets by thecoating member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the entire image forming system in whichan image forming apparatus is connected to a booklet binding apparatus.

FIG. 2 is a front sectional view of booklet binding apparatus.

FIG. 3 is an explanatory drawing (1) of a booklet binding process.

FIG. 4 is an explanatory drawing (2) of a booklet binding process.

FIG. 5 is an explanatory drawing (3) of a booklet binding process.

FIG. 6 is a top view of coating unit 60 of FIG. 1.

FIG. 7 is a sectional view taken on line X-X of FIG. 6.

FIG. 8 is a sectional view taken on line Y-Y of FIG. 6.

FIG. 9 is a control diagram of the booklet binding apparatus.

FIG. 10 is a schematic process diagram for attaching the coating rollerand the leveling roller to the spine surface of a sheet bundle and fordetaching them from the surface.

FIG. 11 is another preferred embodiment (1) of an attaching anddetaching mechanism.

FIG. 12 is still another preferred embodiment (2) of an attaching anddetaching mechanism.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

One of the preferred embodiments of the present invention will beexplained below referring to drawings.

It should be made clear that the following description does not imposerestrictions on the technical scope or terminology of what is claimed.The assertive description in the embodiment of the present inventionindicates the best mode, without the terminology or technical scope ofthe present invention being restricted thereby.

FIG. 1 is a schematic view of the entire image forming system in whichan image forming apparatus A is connected to a booklet binding apparatusB relating to a preferred embodiment of the present invention.

The image forming apparatus A will be explained first.

Image forming apparatus A electrophotographically forms images on sheetswhich are transfer materials and is equipped with image forming sectionA1, document feeder A2, and image reader A3.

Image forming section A1 has charging unit 2, exposing unit 3,developing unit 4, transfer unit 5A, separating unit 5B, and cleaningunit 6 around drum-shaped photoreceptor 1. These electrophotographicunits perform charging, exposure, development, and transferring in orderto form a toner image on the surface of photoreceptor 1 and an image onsheet S.

Sheets S are stored in three sheet trays 7A, and delivered one by onefrom trays 7A to transfer unit 5A. Sheet S receives a toner image therefrom photoreceptor 1 by transfer unit 5A.

Sheet S with a toner image transferred on it is delivered by conveyingbelt 7B to fixing unit 8 and fixed there. Fixed sheet S is ejected byejection rollers 7C or delivered to sheet re-feeding path 7E.

When sheet S is ejected with its face up, switching gate 7D deliverssheet S straight. When sheet S is ejected with its face down or whensheet S has images on both surfaces, switching gate 7D delivers sheet Sdownward.

When sheet S is ejected with its face down, sheet S is guided downward,switched back to move up, and ejected by ejection rollers 7C.

In the double-sided print mode, sheet S is guided downward, turnedupside down with a switchback, delivered to a transfer section whichincludes transfer unit 5A through the sheet re-feeding path 7E, andreceives another image on the other surface of sheet S. Then sheet S issent to fixing device 8, and fixed there, and then ejected.

Document feeder A2 feeds documents one by one to a reading position.Image reader A3 reads the image on a document which is fed from documentfeeder A2 or placed on document table 9 and generates an image signal.

Then, booklet binding apparatus B is outlined below with reference toFIG. 1.

Booklet binding apparatus B receives sheets S from image formingapparatus A, bundles them into a sheet bundle S1, bonds a sheet forcover sheet S2 (hereinafter, simply called a cover sheet) to sheetbundle S1, and thus forms booklet S3.

Booklet binding apparatus B is equipped with sheet conveying section 10which delivers sheet S ejected from image forming apparatus A toejection tray 20 or sheet reversing section 40, clamp unit 50 whichreceives one or more sheets S, bundles them into sheet bundle S1, andclamps the bundle, coating unit 60 which applies adhesive such as ahot-melt adhesive to the spine surface of sheet bundle S1, cover sheetstorage section 70 which stores cover sheets S2, cover sheet supportingunit 80 which receives cover sheet S2 from cover sheet storage section70 and support thereof, and booklet ejecting section 100.

Sheet S ejected from image forming apparatus A is delivered to switchinggate 11 in sheet conveying section 10. The switching gate 11 changessheet paths to send sheet S to ejection tray 20 via ejection path 12 orto sheet reversing section 40. In the non-bookbinding mode, sheets S areejected to ejection tray 20.

In the bookbinding mode, sheet S is sent to sheet reversing section 40via sheet conveying path 13, switched back by sheet reversing section40, and delivered to clamp unit 50. When a preset number of sheets arestacked in clamp unit 50, sheet bundle S1 is turned and held almostvertically.

Coating unit 60 applies adhesive to the bottom surface of sheet bundleS1 which is held vertically.

Cover sheet S2 supplied from cover sheet storage section 70 and beingsupported by cover sheet supporting unit 80 is raised, brought intocontact with sheet bundle S1 which has been coated with adhesive to bebonded to it.

Booklet S3 made by bonding cover sheet S2 to sheet bundle S1 is ejectedto booklet ejecting section 100.

Booklet binding apparatus B in the bookbinding mode will be explainedbelow in more details with reference to FIG. 2.

FIG. 2 is a front sectional view of booklet binding apparatus B.

Sheet S conveyed through sheet conveying path 13 moves diagonally upwardby conveying rollers 401 and 402 on tilted reversing plate 403, thenmoves downward by the reverse rotation of conveying rollers 402, bumpsinto stopper 404, and stops there.

When a predetermined number of sheets S are stacked on reversing plate403, feed-in rollers 405 which have been separated from each other, nipthe sheets S, and carry them downward. The sheets are supported at aslant by clamp unit 50 which is equipped with supporting plate 502 andstopping plate 503.

As to be explained later, after clamping sheet bundle S1 the tiltedclamp unit 50 stands vertically. Adhesive is applied to the spinesurface of sheet bundle S1 and cover sheet S2 is bonded to sheet bundleS1. This completes booklet S3. During a time interval before clamp unit50 returns to the tilted position again, no sheet S cannot be fed intoclamp unit 50. Incoming sheets S must be stood by on reversing plate 403during this time interval. The number of sheets stood by on thereversing plate 403 is equivalent to the aforementioned predeterminednumber of sheets.

The booklet S3 is completed and after returning to the tilted position,clamp unit 50 can stack sheets S thereon. Each sheet S fed by sheetconveying rollers 401 is one by one delivered into clamp unit 50 bysheet conveying rollers 402 until reversing plate 403 receives a presetnumber of sheets which have been preset to form a booklet at theoperation and display unit A5 (see FIG. 1) of image forming apparatus A.

When a preset number of sheets have been stacked in clamp unit 50, thesheet bundle S1 is clamped between supporting plate 502 and clamp plate504 driven by a driving unit (not shown in the figure) and turned tostand vertically from the tilted state when clamp unit 50 rotates aroundaxis 505.

When sheet bundle S1 stands vertically, stopping plate 503 retracts andcoating unit 60 moves perpendicularly to the sheet surface on which FIG.2 is illustrated to apply adhesive to the spine surface of sheet bundleS1.

Then, cover sheet S2 is delivered from sheet tray 701 of cover sheetstorage section 70 provided in a lower portion of booklet bindingapparatus B by delivery rollers 702, held flat horizontally on coversheet supporting unit 80, and lifted up until it is brought into contactwith the spine surface of sheet bundle S1 with lifting unit 90, and thenbonded there to make a booklet S3. The resulting booklet S3 is ejectedto booklet ejecting section 100.

The following describes the details of the process of binding a bookletS3 with reference to FIG. 3, FIG. 4, and FIG. 5.

As already explained, in FIG. 3(a), the sheets S having been conveyedfrom the image forming apparatus A are delivered diagonally upward bythe sheet conveying rollers 401 and 402, and are stacked on the sheetreversing section 40 until a predetermined number is reached. Afterthat, the sheets S are fed diagonally downward by the feed-in roller405, and are stacked on the supporting plate 502 of clamp unit 50.

After a predetermined number of sheets S have been stacked on thesupporting plate 502 one by one, the sheet bundle S1 is clamped by thesupporting plate 502 through the operation of the clamp plate 504. Afterhaving been clamped, the sheet bundle S1 in the tilted position isplaced upright, and the stopping plate 503 retracts. While movingperpendicularly to the sheet surface of FIG. 3, the coating unit 60applies adhesive such as a hot-melt adhesive to the spine surface SA ofthe sheet bundle S1 (see FIG. 3(b)).

The structure and operation of the coating unit 60 characteristic of thepresent invention will be described later.

As shown in the lower part of FIG. 3(c), in parallel with theaforementioned series of operations, the cover sheet S2 conveyed fromcover sheet storage section 70 (see FIG. 2) is fed into a predeterminedposition by the cover sheet feed-in rollers 801 and 802 and are placedin a horizontal position.

After application of the adhesive to the spine surface SA of the sheetbundle S1, the lifting unit 90 (see FIG. 2) lifts the cover sheetsupporting unit 80 until the fixing plate 803 is engaged with the spinesurface SA of sheet bundle S1 through the cover sheet S2.

As shown in the upper part of FIG. 3(c), to prevent the cover sheet S2from being pulled by a pair of folding members 804 provided above thefixing plate 803 and the cover sheet feed-in rollers 801 and 802, thenipping of cover sheet feed-in rollers 801 and 802 is releasedinterlocked with the rising of the cover sheet supporting unit 80.

When the fixing plate 803 is engaged with the spine surface SA of sheetbundle S1, the pair of folding members 804 move closer to each other, asshown in FIG. 4(a), and the cover sheet S2 is bonded with sheet bundleS1 in a rectangular form. Then the folding members go back to theinitial position.

When the cover sheet S2 has been bonded to the sheet bundle S1, thecover sheet supporting unit 80 starts to go down. In synchronism withthis movement, the follower roller supporting levers 805 and 806 of thecover sheet feed-in rollers 801 and 802 rotate in opposite directions,clockwise and counterclockwise, respectively, shown in FIG. 4. The coversheet supporting levers 807 and 808 also rotate clockwise andcounterclockwise to support sheet cover S2.

As will be explained later, the booklet conveyor 810 movesperpendicularly to the sheet surface of FIG. 4 to receive and eject thebooklet S3 having been bound. In this case, the cover sheet supportingunit 80 goes down until the booklet conveyor 810 does not touch the edgeof the cover sheet S2.

When cover sheet supporting unit 80 has moved down, the pair of bookletconveyors 810 having retracted outwardly of the length (width) of thesheet bundle S1 in the direction perpendicular to the sheet surface ofFIG. 4 come closer to each other until they reach the position ofsupporting the sheet bundle S1 (see FIG. 4(b)).

After the movement of the booklet conveyor 810 ends, to alleviate theshock of the booklet S3 falling on the booklet conveyor 810, the bookletconveyor 810 comes closer to the spine surface SA of the sheet bundle S1and stops there (see FIG. 4(c)).

After the cover sheet supporting unit 80 has stopped, the clamp plate504 unclamps the sheet bundle S1 to allow booklet S3 to fall onto thebooklet conveyor 810 (see FIG. 5(a)). In this case, cover sheetsupporting lever 808 is back in an initial horizontal position.

After the booklet S3 has fallen on booklet conveyor 810, the cover sheetsupporting unit 80 starts to go down. The booklet S1 led by its spinesurface SA is fed (see FIG. 5(b)) while falling onto the conveyor 810running in the arrow direction shown in FIG. 5(b). The booklet S3 thenlies flat on the conveyor 810, and is ejected out of the apparatus (seeFIG. 5(c)).

When the booklet S3 has been ejected, the aforementioned componentmembers return to their initial positions.

The following describes the coating unit 60 with reference to FIG. 6,FIG. 7, and FIG. 8.

FIG. 6 is a top view of the coating unit 60 given in FIG. 1. FIG. 7 is asectional view taken on the line X-X of FIG. 6. FIG. 8 is a sectionalview taken on the line Y-Y of FIG. 6.

As shown in FIG. 6, 601 denotes a coating roller as a coating member toapply adhesive. This roller is rotatably supported by the first swingingunit 602 designed in an approximately box-like form. As shown in FIG. 8,part of the coating roller 601 is immersed in the adhesive AD such as ahot-melt adhesive, which is stored in the first swinging unit 602 and ismelted by a heater 603.

As shown in FIG. 6 and FIG. 7, the reference numeral 604 indicates aleveling roller for smoothening the adhesive applied to spine surface SAof sheet bundle S1. The leveling roller 604 is rotatably supported bythe first swinging unit 602 and the approximately box-shaped secondswinging unit 605. A gear G1 is mounted on the rotary shaft 604A of theleveling roller 604.

As shown in FIG. 6, the gear G1 is engaged with the gear G3 fastened tothe rotary shaft 601A of the coating roller 601 through the idle gearG2. Further, as shown in FIG. 7, the gear G1 is engaged with the gear G4which is fastened to the output shaft of the coating motor Ml held bythe second swinging unit 605.

This configuration allows the rotation of the coating motor M1 to betransmitted to the coating roller 601 and the leveling roller 604.

As shown in FIG. 6 and FIG. 7, numeral 606 indicates an approximatelybox-shaped coating unit body provided outside the second swinging unit605. This unit rotatably supports the second swinging shaft 607 fastenedto the second swinging unit 605.

Further, as shown in FIG. 6 and FIG. 7, four slide bearings 608 areprovided on upper portions of the coating unit 606 and are slidablyengaged with the slide shafts 609 and 610. The slide shafts 609 and 610are so disposed that the coating unit 606 can travel perpendicularly tothe sheet surface of FIG. 1.

As shown in FIG. 6, numeral 611 represents the belt for allowing thecoating unit 606 to slide. One part of the belt 611 is fastened to oneof the slide bearings 608 through a linking member 612.

The belt 611 is engaged with the pulleys 613 and 614 which are providedin parallel with the slide shafts 609 and 610. The pulley 614 is drivenby the traveling motor M2.

As shown in FIG. 8, the reference numeral 615 indicates a first solenoidfor causing the first swinging unit 602 of FIG. 8 to swingcounterclockwise around the rotary shaft 604A of the leveling roller604. This solenoid is fastened to the second swinging unit 605. Thereference numeral 616 denotes a second solenoid for causing the secondswinging unit 605 (in FIG. 8) to swing clockwise around the secondswinging shaft 607 arranged rotatably on the coating unit 606. Thissolenoid is fastened to the coating unit 606.

As illustrated in FIG. 8, the strokes of plungers of the first solenoid615 and second solenoid 616 are set to ensure that the peripheries ofcoating roller 601 and leveling roller 604 will have the same height totouch spine surface SA of sheet bundle S1, when the first solenoid 615and second solenoid 616 are energized and their plungers pop up.

As shown in FIG. 8, numeral 617 indicates a detection device fordetecting the sides SS1 and SS2 of sheet bundle S1 positionedperpendicular to spine surface SA of the sheet bundle S1. The device 617is provided integrally on the front side of the coating unit 606 in thedirection indicated by an arrow.

Similarly, in FIG. 8, numeral 618 indicates a regulating plate forregulating the quantity of the adhesives AD stuck to the surface ofcoating roller 601 and is provided at a preset clearance from thecoating roller 601. The reference numeral 619 denotes a scraper platefor removing the adhesive AD from the leveling roller 604, and is heldin engagement with the leveling roller 604 at a predetermined pressure.

Both the coating roller 601 and leveling roller 604 are designed torotate in the arrow direction of FIG. 8.

It should be noted that the coating roller 601 houses a rod-like heater(not illustrated).

As is clear from the aforementioned description, the clamp unit 50 isequipped with a clamp plate 504, a supporting plate 502 and others. Thecoating unit 60 is equipped with a coating roller 601, a leveling roller604, a coating motor Ml and others. The traveling unit 61 includes aslide bearing 608, slide shafts 609 and 610, a belt 611, a travelingmotor M2 and others. The attaching and detaching mechanism is providedwith a first solenoid 615. The mechanism to attach and detach theleveling member is equipped with a second solenoid 616. The cover sheetsupporting unit 80 includes cover sheet feed-in rollers 801 and 802, afixing plate 803, a folding member 804, follower roller supportinglevers 805 and 806, cover sheet supporting levers 807 and 808, and abooklet conveyor 810.

Referring to FIG. 9, the following describes the control-relatedconfiguration of the booklet binding apparatus B characterized by theaforementioned structure.

The reference numeral B1 represents a control unit of the bookletbinding apparatus B, and is equipped with a memory B2 which stores theprocedures and data for controlling the booklet binding apparatus B, aCPU (reference numeral B3) which executes control according to thecontrol procedures and data in the memory B2, and others.

Control unit B1 is designed capable of communicating with the controlunit A4 (see FIG. 1) of the superordinate image forming apparatus A viathe interface B4, and receives information on the sheet size and thepreset number of sheets. The input side of the control unit B1 isconnected with the detection device 617. The output side is connectedwith a clamp unit 50, a coating motor M1, a traveling motor M2, a firstsolenoid 615, a second solenoid 616 and others.

The control unit B1 receives electric power such as the AC, for example,from other power supply line PL and supplies predetermined power to thefirst solenoid 615, second solenoid 616, and other components via thepower supply unit B5 provided in the control unit B1.

The following describes the procedures for applying adhesive in thebooklet binding apparatus B of the aforementioned structure withreference to FIG. 10 and other aforementioned drawings:

FIG. 10 is a schematic diagram representing the process of moving thecoating roller 601 and the leveling roller 604 to and from the spinesurface SA of a sheet bundle S1.

The coating unit 60 stands by at the initial position corresponding tothe left portion of FIG. 10, while the coating roller 601 and levelingroller 604 are rotating.

As shown in FIG. 3(a), when the sheet bundle S1 is set upright by theclamp unit 50, the traveling motor M2 (see FIG. 6) rotates to move thecoating unit 60 to the right in FIG. 10.

The coating unit 60 moves and the detection device 617 detects the sideSS1 of the sheet bundle S1. When a predetermined time (T1) has passedthereafter, the first solenoid 615 actuates (see FIG. 8) to move thecoating roller 601 to an end of the spine surface SA of the sheetbundle, whereby adhesive is applied to the spine surface.Simultaneously, the second solenoid 616 also actuates, and the levelingroller 604 is moved up to a workable position for the levelingoperation.

The coating unit 606 moves and the detection device 617 detects the sideSS2 of the sheet bundle S1. When a predetermined time (T2) has passedthereafter, the first solenoid 615 becomes inactivated, and the coatingroller 601 is detached from the end of the spine surface SA of the sheetbundle S1.

Similarly, when a predetermined time (T3) has passed subsequent to thedetection of the side SS2 of the sheet bundle S1 by the detection device617, the second solenoid 616 becomes inactivated, and the levelingroller 604 is detached from the end of the spine surface SA, whereby theadhesive leveling operation terminates.

In the return process subsequent to coating and leveling operations, thecoating roller 601 and leveling roller 604 are controlled to be detachedfrom the spine surface SA of the sheet bundle, and to return to theirinitial positions.

In the aforementioned structure, for example, if the power supply fromthe power line PL is suspended during the process of coating theadhesive AD, due to power failure, inadvertent interruption of theoperation of the booklet binding apparatus B, or a trouble of the powersupply unit B5, the power supply to the first solenoid 615 and secondsolenoid 616 is discontinued, and their plungers retract. At the sametime, the coating roller 601 and leveling roller 604 are automaticallyseparated from the spine surface SA of the sheet bundle S1 by the weightof the coating unit 60.

In the aforementioned embodiment, the separation mechanism can bedefined as follows.

When power supplied to the first solenoid 615 and second solenoid 616 isshut off, the first swinging unit 602 and second swinging unit 605 aremade to rotate around the rotary shaft 604A of the leveling roller 604and second swinging shaft 607, respectively, by the weight of thecoating unit 60, whereby the coating roller 601 and leveling roller 604are separated from the spine surface SA of the sheet bundle S1.

As explained above, the present embodiment is provided with a mechanismfor separating the coating roller 601 and leveling roller 604 from thespine surface SA of the sheet bundle S1 when an abnormal incident occursduring the process of applying adhesives AD. This arrangement eliminatesa trouble of the coating roller 601 and leveling roller 604 being leftattached to the spine surface SA of the sheet bundle S1. This ensureseasy recovery of the booklet binding apparatus from a trouble.

In the aforementioned embodiment, the coating unit 60 includes both thecoating roller 601 and leveling roller 604. It is also possible to makesuch arrangements that the coating unit 60 includes the coating roller601 alone.

Further, in the aforementioned embodiment, binding of the booklet S3 isachieved by bonding the cover sheet S2 to he sheet bundle S1. It is alsopossible to bind a booklet by bonding sheet bundle S1 alone withadhesive.

Further, the solenoid as an attaching and detaching mechanism can bereplaced by an eccentric cam 620 given in FIG. 11, for verticaltraveling of the first swinging unit 602. In this configuration, thecoating roller 601 touches the spine surface SA of the sheet bundle justbefore the eccentric cam 620 reaches the highest position (upper deadpoint). Thus, if an abnormal incident occurs during the application ofadhesive and it discontinues the supply of power to the drive motor(without a reference number) for driving the eccentric cam 620, theeccentric cam 620 is rotated in the arrow direction by the weight ofcoating unit 60, with the result that the coating roller 601 isseparated from the spine surface SA of the sheet bundle S1.

The second swinging unit 605 (see FIG. 8) has a similar attaching anddetaching function, and the description thereof will be omitted to avoidduplication.

In addition to the aforementioned examples, links 630 and 631 can beused as the attaching and detaching mechanism to move the coating unit60 to and from the spine surface SA of the sheet bundle, as shown inFIG. 12. In this configuration, the coating roller 601 touches the spinesurface SA of the sheet bundle S1 just before the dead point DP of thelinks 630 and 631. If an abnormal incident occurs during application ofthe adhesive and it discontinues the supply of power to the drive motor(without reference number) for driving the links 630 and 631, the links630 and 631 are inclined in the arrow-marked direction by the weight ofcoating unit 60, with the result that the coating roller 601 is detachedfrom the spine surface SA of the sheet bundle S1.

The second swinging unit 605 (see FIG. 8) can be configured in thesimilar manner, and the description thereof will be omitted avoidduplication.

1. A booklet binding apparatus comprising: a clamp mechanism forclamping a bundle of sheets; a coating member for coating adhesive on anend surface of the bundle of sheets clamped by the clamp mechanism; anattaching and detaching mechanism for attaching the coating member tothe end surface of the bundle of sheets and for detaching the coatingmember from the end surface; and a separation mechanism for detachingthe coating member from the end surface of the bundle of sheets, when anabnormal incident occurs during coating of adhesive on the end surfaceof the bundle of sheets by the coating member.
 2. The booklet bindingapparatus of claim 1, wherein the attaching and detaching mechanism hasa solenoid for attaching the coating member to an end surface of abundle of sheets and for detaching the coating member from the endsurface, and the separation mechanism detaches the coating member fromthe end surface of the bundle of sheets by cutting off electricitysupply to the solenoid.
 3. The booklet binding apparatus of claim 1,wherein the attaching and detaching mechanism has a cam for attachingthe coating member to an end surface of a bundle of sheets and fordetaching the coating member from the end surface, and the separationmechanism detaches the coating member from the end surface of the bundleof sheets by cutting off driving force to the cam.
 4. The bookletbinding apparatus of claim 1, wherein the attaching and detachingmechanism has a link mechanism for attaching the coating member to anend surface of a bundle of sheets and for detaching the coating memberfrom the end surface, and the separation mechanism detaches the coatingmember from the end surface of the bundle of sheets by cutting offdriving force to the link mechanism.
 5. An image forming systemcomprising: an image forming apparatus having an image forming sectionfor forming an image on a sheet; a booklet binding apparatus forproducing a booklet by receiving a plurality of sheets from the imageforming apparatus, the booklet binding apparatus comprising; a clampmechanism for clamping a bundle of sheets; a coating member for coatingadhesive on an end surface of the bundle of sheets clamped by the clampmechanism; an attaching and detaching mechanism for attaching thecoating member to the end surface of the bundle of sheets and fordetaching the coating member from the end surface; and a separationmechanism for detaching the coating member from the end surface of thebundle of sheets, when an abnormal incident occurs during coating ofadhesive on the end surface of the bundle of sheets by the coatingmember.
 6. The image forming system of claim 5, wherein the attachingand detaching mechanism has a solenoid for attaching the coating memberto an end surface of a bundle of sheets and for detaching the coatingmember from the end surface, and the separation mechanism detaches thecoating member from the end surface of the bundle of sheets by cuttingoff electricity supply to the solenoid.
 7. The image forming system ofclaim 5, wherein the attaching and detaching mechanism has a cam forattaching the coating member to an end surface of a bundle of sheets andfor detaching the coating member from the end surface, and theseparation mechanism detaches the coating member from the end surface ofthe bundle of sheets by cutting off driving force to the cam.
 8. Theimage forming system of claim 5, wherein the attaching and detachingmechanism has a link mechanism for attaching the coating member to anend surface of a bundle of sheets and for detaching the coating memberfrom the end surface, and the separation mechanism detaches the coatingmember from the end surface of the bundle of sheets by cutting offdriving force to the link mechanism.